as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Recent Examples of insidious
Adding layers of bureaucratic chaos will have the insidious effect of discouraging people from following the law.
—
Editorial Board, Washington Post, 27 May 2026
The result is a particularly insidious failure mode.
—Tomas Chamorro-Premuzic, Forbes.com, 27 May 2026
Meanwhile, Cole’s quietly insidious plot unfolds around her with unnerving precision (although a handful of secondary characters sometimes swallow too much momentum), and that patience pays off enormously.
—Alison Foreman, IndieWire, 17 May 2026
And now the sort of very insidious paradox here is that when, not if, when Black representation is halved in the next year or two, in the next couple cycles, that will not be able to be used as a rationale for fixing that problem.
—Hanna Rosin, The Atlantic, 14 May 2026
See All Example Sentences for insidious
Editorial Board, Washington Post, 27 May 2026
The result is a particularly insidious failure mode.
—Tomas Chamorro-Premuzic, Forbes.com, 27 May 2026
Meanwhile, Cole’s quietly insidious plot unfolds around her with unnerving precision (although a handful of secondary characters sometimes swallow too much momentum), and that patience pays off enormously.
—Alison Foreman, IndieWire, 17 May 2026
And now the sort of very insidious paradox here is that when, not if, when Black representation is halved in the next year or two, in the next couple cycles, that will not be able to be used as a rationale for fixing that problem.
—Hanna Rosin, The Atlantic, 14 May 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
-
This has significantly weakened the Indian rupee against the dollar at a time when global oil prices are rising, creating a treacherous situation for India, which imports more 85% of its crude requirements.—
Priyanka Salve,
CNBC,
9 June 2026
-
Dunn and the clinic’s vaccinator, Moses Yambie, then took a motorbike 30 miles across a treacherous route at night to transport the infant to the nearby hospital.—
Imani Cruzen,
Twin Cities,
7 June 2026
Adjective
-
The perpetual buzz of mining bees mingled with the shuffle of rabbits through the bushes, woodpeckers’ rapid-fire drilling, and the hard-staccato tchack, tchack, tchack of ravenlike birds known as jackdaws, creating a subtle symphony.—
Literary Hub,
Literary Hub,
11 June 2026
-
Look for alcohol-free, subtle formulas the goal is a whisper of fragrance, not a perfume cloud that announces itself from across the room.—
Lauren Jarvis-Gibson,
Miami Herald,
10 June 2026
Adjective
-
Baldoni denied the allegations and maintained that Lively's claims were false.—
Janelle Ash , Lauryn Overhultz,
FOXNews.com,
13 June 2026
-
Baldoni filed a countersuit in January 2025 for civil extortion, defamation and false light.—
Liza Esquibias,
USA Today,
12 June 2026
Adjective
-
The deceptive piece is the marketing.—
Kansas City Star,
Kansas City Star,
8 June 2026
-
Manaea’s delivery is deceptive because there is crossfire action from a low slot.—
Will Sammon,
New York Times,
5 June 2026
Adjective
-
This is perhaps the most perfidious practice of this sort of politics.—
David M. Drucker,
Twin Cities,
3 June 2026
-
Pakistan was a perfidious ‘ally’ in Afghanistan, backing the Taliban while pretending to be our friends.—
Efrat Lachter,
FOXNews.com,
18 Apr. 2026
Adjective
-
The inspectors also noted improper date marking and incorrect food storage practices.—
Shambhavi Rimal,
Fort Worth Star-Telegram,
10 June 2026
-
According to prosecutors, Kroger initially miscalculated the calorie content of the products when they were introduced in 2021 and displayed incorrect calorie values on both FDA nutrition labels and front-of-package advertising.—
ABC News,
ABC News,
8 June 2026
Adjective
-
Wirskye then asked who was wrong that day.—
Dawn White,
CBS News,
7 June 2026
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Lauren McCormick, a spokeswoman for travel insurance provider Squaremouth, says your phone is the most efficient tool for protecting your travel investment if things go wrong.—
Christopher Elliott,
Forbes.com,
6 June 2026
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 13 Jun. 2026.
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